CaCl2 Concentration Research Articles

Effect of chemical pretreatment on quality attributes of the cashew apple.

Cashew apples, tropical pseudo fruit, are rich in bioactive compounds. It is still underutilized due to its high perishability and its astringent flavor. This study aims to extend its shelf life by chemical dip and dry method at the rural level. Inhibition of fruit-spoiling enzymes, such as polyphenol oxidase (PPO), peroxidase (POD), amylase, and cellulase, was a significant response in this method. Enzyme inhibition was carried out using chemicals: NaCl (1-10mM), CaCl2 (1-10mM), and ethylenediamine tetraacetic acid (0.1-1mM). The effect of chemical concentration and dipping time was studied using a full factorial method at three levels (-1, 0, and 1). The dipping time ranged from 60 to 180min, and chemical concentrations from 1 to 10mM were studied. Optimal treatment conditions were obtained as follows: NaCl concentration of 9.45mM, dipping time of 160min, and CaCl2 concentration of 7.8mM, dipping time of 160min. NaCl pretreatment showed maximum inhibition of PPO (>80%) and POD (>80%), whereas CaCl2 pretreatment showed maximum inhibition of amylase (60.58%) and cellulase (80.23%). Hence, to avoid postharvest losses, pretreatment with NaCl and CaCl2 was adequate to preserve the texture and color of cashew apples. PRACTICAL APPLICATION: Chemical pretreatment can prevent the postharvest losses of cashew apples. Inhibition of PPO, POD, amylase, and cellulase is vital in the shelf-life extension of cashew apples. Sodium chloride dip is a cost-effective method for increasing the storability of cashew apples.

Wet-spinnability and crosslinked Fiber properties of alginate/hydroxyethyl cellulose with varied proportion for potential use in tendon tissue engineering

Researchers have examined different bio-inspired materials in tissue engineering and regenerative medicine to fabricate scaffolds to address tendon regeneration requirements. We developed fibers based on alginate (Alg) and hydroxyethyl cellulose (HEC) by wet-spinning technique to mimic the fibrous sheath of ECM. Various proportions (25:75, 50:50, 75:25) of 1 % Alg and 4 % HEC were blended to this aim. Two steps of crosslinking with different concentrations of CaCl2 (2.5 and 5 %) and glutaraldehyde (2.5 %) were used to improve physical and mechanical properties. The fibers were characterized by FTIR, SEM, swelling, degradation, and tensile tests. The in vitro proliferation, viability, and migration of tenocytes on the fibers were also evaluated. Moreover, the biocompatibility of implanted fibers was investigated in an animal model. The results showed ionic and covalent molecular interactions between the components. In addition, by properly maintaining surface morphology, fiber alignment, and swelling, lower concentrations of HEC in the blending provided good degradability and mechanical features. The mechanical strength of fibers was in the range of collagenous fibers. Increasing the crosslinking led to significantly different mechanical behaviors in terms of tensile strength and elongation at break. Because of good in vitro and in vivo biocompatibility, tenocyte proliferation, and migration, the biological macromolecular fibers could serve as desirable tendon substitutes. This study provides more practical insight into tendon tissue engineering in translational medicine.

Biodegradable form stable phase change material for cold storage packaging of meat

In this study, tetradecane was selected as a phase change material (PCM) to provide a thermal buffering system for meat packaging. Firstly, tetradecane was capsulated within a calcium alginate shell; then the conditions for achieving the highest efficiency were obtained. The capsules were characterized using Scanning electron microscopy, Thermo-gravimetric analysis and Differential scanning calorimetry. The results revealed the stability of the thermal properties of the encapsulated PCMs and the efficient capsulation of tetradecane in the capsules. Next, the alginate films were prepared using various concentrations of sodium alginate (SA) and CaCl2 incorporated with capsulated tetradecane. Observations indicated that the film prepared with 5% SA and 12% CaCl2 had the least leakage and the best structural integration during phase change cycles and storage at 25 °C. The use of PCM-incorporated packages could successfully delay the meat temperature elevation during phase change cycles and incubation at 25 °C. After 7.5 h incubation at 25 °C and 15 phase change cycles, PCM-incorporated samples had lower weight loss and higher hardness, gumminess and chewiness as compared to the control. Further, the physicochemical parameters of the meat in PCM-incorporated package were less changed, as compared to the fresh sample. So, the prepared package could be effectively used in meat packaging.

Effects of CaCl2 concentration on fibrils formation and characteristics of soybean protein isolate and β-conglycinin/glycinin

In this study, fibrillation of soybean protein isolate (SPI) and β-conglycinin (7S)/glycinin (11S) in acid-heating with CaCl2 concentration (0–200 mM) was explored. Fibril formation kinetics results showed the fastest fibril formation rate and the most fibrils with 80 mM CaCl2 addition. Fourier-transform infrared (FTIR) spectroscopy, size distribution and Transmission electron microscopy (TEM) results demonstrated SPI fibril structure became more complete and occurred entanglement with CaCl2 concentration increasing from 0 to 80 mM. When CaCl2 addition was above 80 mM, ζ-potential, surface hydrophobicity (H0) and free sulphydryl groups determination proved hydrophobic interaction among fibril built-units was hindered by charges shielded effect, and basic units of 11S were more exposed, aggregate morphology were changed to thicker fibrils or amorphous aggregates. The whole system with CaCl2 has preferable antioxidant property and no cytotoxicity. The study provided a basis for optimizing SPI fibrillation in food industry.

Tetracycline removal from aqueous solution through photoelectrochemical oxidation process using Bi2O3/ZIF-67@GP under visible light irradiation: Effects of operational parameters, water matrix

Tetracycline degradation was investigated using two promising technologies of photocatalysis and photoelectrochemical oxidation through Bi2O3/ZIF-67 nanocomposite coating on a graphite plat (Bi2O3/ZIF-67@GP). The physical, chemical and morphological properties of coated graphite plat were determined by XRD, SEM, EDX, CROSS, UV–Vis DRS, and PL. Photocatalytic process in optimal process conditions (pH=4.1, pollutant concentration/load of photocatalyst =0.26 mg.m2/g.L and irradiation time=86 min) showed 77% pollutant removal efficiency. The use of photoelectrochemical oxidation processes has a positive effect on the efficiency of pollutant removal, at optimal conditions (Electrode distance=5.5 mm, pH=4, voltage=1.8 V, Time=89 min, and pollutant concentration/photocatalyst load= 0.2 mg.m2/g.L), the result was showed that 97% tetracycline removal efficiency. The effect of the water matrix including NaCl, Na2SO4, NaHCO3, KCl, MgSO4, and CaCl2 in different concentrations (100–800 mg/L) was recast the initial pH=7, and the pollutant concentration/photocatalyst load=0.2 mg.m2/g.L, and the time=90 min. The investigation and results showed that the presence of inorganic cations and anions caused a constant decrease in the reaction rate.

Effect of optimized germination technology on polyphenol content and hypoglycemic activity of mung bean.

The study aimed to investigate the effect of germination conditions on the content of polyphenol extract in mung bean and to further investigate the effect of polyphenol extract in germinated mung bean on diabetic mice. Through single factor experiment and response surface experiment, the effects of soaking temperature, soaking time, germination temperature, germination time and soaking liquid CaCl2 concentration on the polyphenol content of mung bean were analyzed. The optimal germination conditions of mung bean were determined as soaking temperature 25°C, soaking time 11 h, germination temperature 28°C, germination time 3 days and CaCl2 concentration 2 mM. Under these conditions, the content of polyphenol extract in germinated mung bean was 4.878 ± 0.30 mg/g, which was 3.07 times higher than that in ungerminated mung bean. The structure and content of purified polyphenols in germinated mung bean were determined by HPLC-MS/MS. Quinic acid, Quercetin, Rutin, Vitexin, Isovitexin and other substances were identified, and the content of polyphenols was 65.19%. In addition, through the in vivo and in vitro hypoglycemic activity experimental study of germinated mung bean polyphenols extract, the results showed that germinated mung bean polyphenols had an in vitro inhibitory effect on α-glucosidase, IC50 was 44.45 mg/ml. In vitro inhibitory activity was stronger after digestion. Polyphenol extract can significantly reduce blood sugar and improve insulin resistance in Type 2 diabetic mice (T2DM). According to the results, germination treatment is an effective way to increase the content of polyphenols in mung bean, and the polyphenols extract has hypoglycemic activity.

Vacuum extraction of high-salinity water for the determination of oxygen and hydrogen isotopic compositions using cavity ring-down spectroscopy

Tracking the hydrogen and oxygen isotopic compositions of water samples can aid in understanding the water cycle. Compared to that of fresh water, analyzing the hydrogen and oxygen isotopic composition of high-salinity water is still a challenging task owing to the influence of dissolved salts. In this study, desalination was achieved by vacuum extraction, and the oxygen and hydrogen isotope ratios (δ18O and δ2H) were measured using cavity ring-down spectroscopy (CRDS). Different solutions of the individual salts (NaCl, KCl, MgCl2, and CaCl2) were prepared with deionized water (DI) having a known stable isotopic composition. After vacuum extraction, the maximum differences in isotopic composition was no more than 0.09‰ for δ18O and 0.30‰ for δ2H at 4 mol/L NaCl and KCl and 1 mol/L MgCl2 and CaCl2. The isotopic compositions of two high-salinity samples (IAPSO standard seawater and brine water) were determined by the proposed procedure as well as thermal conversion/elemental analyzer-isotope ratio mass spectrometry for comparison. The δ18O and δ2H results obtained using the two methods were consistent. The influence of isotope-salts was completely overcome by the proposed vacuum extraction desalination procedure. Thus, the method enables the rapid extraction of a large number of samples, regardless of the type and origin of the salt solutions, provided the concentrations of MgCl2 and CaCl2 are below 1.0 mol/L.

Goethite affects phytolith dissolution through clay particle aggregation and pH regulation

Formed in plant tissues as fine silica particles, phytoliths are deposited within plant debris in soils where they can dissolve and feed silicon (Si) fluxes to the biosphere and hydrosphere. Yet, soil phytoliths can be protected from dissolution by entrapment in aggregates, and thus be withdrawn from the global silica cycle. Among clay-sized minerals interacting in stable aggregates, goethite and kaolinite are ubiquitous in soils. We analyzed the impact of goethite-mediated aggregation on the release of aqueous Si from phytoliths entrapped in microaggregates containing organic matter and kaolinite, with quartz and goethite at variable concentrations, simulating a soil sequence with increasing contents of clay and iron oxide, as it can commonly occur in terrestrial ecosystems. The microaggregates stored sizable amount of organic carbon, the release of which decreased with increasing goethite concentration. Aqueous Si was assessed through a kinetic extraction with dilute CaCl2, while pH, aluminum (Al) and germanium (Ge) concentrations were measured in the CaCl2 extracts. Our experimental data showed that phytoliths were the source of aqueous Si. They also showed that the process of phytolith dissolution prevailed over Si adsorption on goethite. As mediated by goethite, aggregation protected phytoliths from dissolution at goethite concentrations above 20 g kg−1. Increasing goethite concentration enhanced aggregation on the one hand, but increased pH from 5.5 to 7.5 on the other. Thus, while aggregation significantly reduced the release of aqueous Si by 1.7- to 3-fold at a given pH, the increase in pH enhanced it. Overall, at common soil solution pH (5–6), aggregation reduced Si release by 2–3 times. Thus, preservation of phytoliths in aggregates can be widespread in well-aerated soils and more effective than Si adsorption on secondary oxides in retaining Si.

Investigating the performance of non-damaging hybrid gel to mitigate lost circulation in fractured formations: A comprehensive study using Box–Behnken design

Gels that have a low viscosity at the time of mixing and form a three-dimensional gel structure after some time delay can be applied successfully in controlling lost circulation. Cross-linked gels play an important role in sealing high permeable and fractured formations. This research aims to evaluate a novel gel that can mitigate lost circulation during drilling in fractured formations. The hybrid gel consists of a cross-linked polymer gel as the continuous phase and an oil as the internal phase. The purpose of designing hybrid gels is to reduce the possibility of formation damage caused by the presence of gel in the fractures. In addition, the use of an internal phase in the gel can increase the durability of the gel and reduce the final cost of the operation.This article consists of two parts, experimental investigation and empirical modeling using response surface methodology. A number of parameters such as initial gelation time, final gelation time, and cross-linking rate were defined to evaluate the gel behavior under different conditions. First, the effect of polymer type, internal phase viscosity, pH, temperature, salinity, and shear rate on the behavior of the hybrid gel was investigated. Furthermore, in order to increase cross-linking efficiency, the cross-linker was added onto the reactive nano-silica surface to achieve a nano-crosslinker, and then the performance evaluation was accomplished. Thereafter, the sealing pressure test was examined to measure the amount of pressure that the hybrid gels could withstand in the fractures to prevent further fluid loss. Finally, the amount of gel rupture in 15% and 28% hydrochloric (HCl) was studied over time at 25 and 60 °C so as to evaluate the formation damage of hybrid gels.Response surface methodology (RSM) was employed based on Box-Behnken design to determine a correlation for predicting the final viscosity of hybrid gel as a function of temperature, pH, and CaCl2 concentration. The predicted model was obtained by solving the quadratic regression model. The value of the correlation coefficient (R2 = 0.90) for the present mathematical model indicated good relation between experimental data and predicted values. Therefore, the proposed model is able to predict the final viscosity of hybrid gel adequately within the limits of input parameters being used.The experimental results show that hybrid gels, due to their flexible viscosity response, long-term stability, and non-damaging properties, can have proper performance and application in industry to combat lost circulation. Nano-crosslinker can effectively increase the cross-linking rate and final viscosity of the gel and also improve the gel performance at high temperatures. Based on dynamic sealing pressure experiments, the value of maximum sealing pressure for the guar-based hybrid gel is higher than that of xanthan. In addition, the nano-crosslinker enhances the maximum tolerable pressure of the gels to seal the fractures.

Effect of a Change in the CaCl2/Pectin Mass Ratio on the Particle Size, Rheology and Physical Stability of Lemon Essential Oil/W Emulgels

A three-step (rotor-stator-microfluidization-rotor stator) protocol was used to prepare 15% lemon essential oil in water emulgels using a mixture of Tween 80 and Span 20 surfactants as low molecular mass emulsifiers and 0.4% low-methoxyl citrus peel pectin as a gelling agent. Ca2+ was used as a gel-promoting agent. Different CaCl2/pectin mass ratio values from 0.3 to 0.7 were used. Emulgels showed a microstructure consisting of oil droplets embedded in a sheared gel matrix, as demonstrated by bright field optical microscopy. Laser diffraction tests showed multimodal particle size distributions due to the coexistence of oil droplets and gel-like particles. Multiple light scattering tests revealed that the physical stability of emulgels was longer as the CaCl2/pectin mass ratio decreased and that different destabilization mechanisms took place. Thus, incipient syneresis became more important with increasing CaCl2 concentration, but a parallel creaming mechanism was detected for CaCl2/pectin mass ratio values above 0.5. Dynamic viscoelastic and steady shear flow properties of the emulgels with the lowest and highest CaCl2/pectin mass ratio values were compared as a function of aging time. The lowest ratio yielded an emulgel with enhanced connectivity among fluid units as indicated by its wider linear viscoelastic region, higher storage modulus, loss modulus and viscosity values, and more shear thinning properties than those of the emulgel formulated with the highest CaCl2/pectin mass ratio. The evolution of the dynamic viscoelastic properties with aging time was consistent with the information provided by monitoring scans of backscattering as a function of sample height.

Synthesis of Alginate Nanoparticles Using Hydrolyzed and Enzyme-Digested Alginate Using the Ionic Gelation and Water-in-Oil Emulsion Method

Alginate nanoparticles (AlgNPs) are attracting increasing interest for a range of applications because of their good biocompatibility and their ability to be functionalized. Alginate is an easily accessible biopolymer which is readily gelled by the addition of cations such as calcium, facilitating a cost-effective and efficient production of nanoparticles. In this study, AlgNPs based on acid hydrolyzed and enzyme-digested alginate were synthesized by using ionic gelation and water-in-oil emulsification, with the goal to optimize key parameters to produce small uniform (<200 nm) AlgNPs. By the ionic gelation method, such AlgNPs were obtained when sample concentrations were 0.095 mg/mL for alginate and CaCl2 in the range of 0.03-0.10 mg/mL. Alginate and CaCl2 concentrations > 0.10 mg/mL resulted in sizes > 200 nm with relatively high dispersity. Sonication in lieu of magnetic stirring proved to further reduce size and increase homogeneity of the nanoparticles. In the water-in-oil emulsification method, nanoparticle growth was confined to inverse micelles in an oil phase, resulting in lower dispersity. Both the ionic gelation and water-in-oil emulsification methods were suitable for producing small uniform AlgNPs that can be further functionalized as required for various applications.

Programmable and printable formaldehyde dehydrogenase as an excellent catalyst for biodegradation of formaldehyde.

As an environmental pollutant, formaldehyde can cause serious harm to the human body. Among many degradation methods, formaldehyde dehydrogenase from Pseudomonas putida (PFDH) exhibits broad potential because of its strong catalytic specificity and high degradation efficiency. However, the real application of PFDH in industry is limited by its instability and difficulties in recycling. In this work, the suitable printing conditions for immobilizing PFDH by three-dimensional (3D) printing technology were studied: the concentration of sodium alginate (SA) was 1.635 wt%, the concentration of CaCl2 was 7.4 wt%, the crosslinking time with CaCl2 was 8 min, and the temperature of the reaction was 31.5°C. 3D-printed PFDH/calcium alginate (CA) microspheres have 210% relative enzyme activity after seven repeated uses. Dried PFDH/CA particles were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), EDS elemental mapping, and thermogravimetric analysis (TGA) which proved that the enzyme was immobilized by the material. In addition, the recycling ability of 3D printing to immobilize different objects was explored and different shapes were designed by computer-aided design (CAD). In conclusion, 3D printing technology was applied to immobilize PFDH in this work, which provides a new idea to biodegrade formaldehyde in a green way.

Understanding the microstructure of a functional meat analogue: Demystifying interactions between fungal hyphae and egg white protein

This study investigated the microstructure and interactions of heat treated concentrated Fusarium venenatum biomass, commonly referred to as ‘mycoprotein’ (MYC), as well as the impact of 3 wt % egg white protein (EWP) on those interactions – EWP being frequently added as a ‘binding agent’. Confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (Cryo-SEM) combined with energy dispersive spectroscopy analysis (EDS) demonstrated the filamentous nature of the MYC, made up of chitin and protein, with a filament aspect ratio typically between 130 and 140. Protein extraction and analysis via SDS-PAGE electrophoresis suggested that the most abundant native protein in the MYC had a molecular weight of 69.2 kDa, probably belonging to the heat shock 70 (HSP70) group. Frequency sweep dynamic shear rheology measurements were performed at combinations of 3 different values of pH (3, 5 and 7), NaCl concentration ([NaCl] = 0, 100 and 200 mM), CaCl2 concentration ([CaCl2] = 0, 50 and 100 mM) and wt. % MYC solids (5, 10, 15 and 20) without added EWP and with added EWP (MYC-EWP). For MYC the storage modulus G′ was seen to increase strongly with increasing wt. % MYC solids but also with [NaCl] and [CaCl2], the latter having greater impact at pH 5 and 7. The opposite trends were observed at pH 3, where G′ decreased with increasing concentration of ions, the highest G′ values for MYC occurring at pH 3 with no added salts. This suggests that electrostatic interactions between the MYC elements are key to the overall texture. On addition of EWP, there was good evidence that EWP completely coats the filaments so that, the hyphal interactions of MYC-EWP are then dominated by the response of EWP to changes in pH and salt composition. Gaining further understanding of the strength and distribution of the loci of these interactions is therefore key to better control of the texture of such meat analogues.

Foliar Calcium Effects on Quality and Primary and Secondary Metabolites of White-Fleshed ‘Lemonato’ Peaches

‘Lemonato’ is a Greek peach melting-flesh white-flesh cultivar with high nutritional value highly appreciated by the consumers. This study aimed to evaluate the effect of pre-harvest foliar calcium application on fruit quality, primary metabolite profile, antioxidant activity, total phenolic content, and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. The experiment was conducted for two years, 2019 and 2020, in two commercial orchards at Kato Lehonia and Agios Vlasios regions, central Greece, where the ‘Lemonato’ clone ‘Stamatis’ is traditionally cultivated. The treatments were organic calcium (Ca), calcium–silicate in nanoparticles (Ca–Si), and calcium chloride (CaCl2). Foliar application of the different Ca formulations, commonly used as a horticultural practice, were not effective at improving the fruit quality characteristics in this clone, which is characterized by fruit softening during ripening. The study revealed the sugars and organic acid composition and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. Peach fruit quality, primary metabolites, and phenolic compounds of the two orchards showed a different response to organic Ca and Ca–Si, indicating that genetic or environmental factors may also be involved. A higher concentration of organic Ca and CaCl2 increased the peach fruit phenolic compounds content and the total antioxidant activity, improving the fruit nutritional quality.

Hybrid salt-enriched micro-sorbents for atmospheric water sorption

Water shortage severely impacts drought-stricken regions, with estimates indicating that almost half a billion people are affected yearly. Composites of Salt and Porous Matrix (CSPMs) are promising functional materials for water vapor sorption. Here, CSPMs were synthesized by loading SAPO-34 porous crystals with highly hygroscopic salts, namely LiCl and CaCl2, individually (mono-salt systems) or combined (binary salt systems) to enhance water sorption capacity and cyclability. The LiCl and CaCl2 content in the impregnation solution impacted the sorption behavior and equilibrium capacity of the resulting composites. Physicochemical, morphological, textural, and sorption properties were evaluated showing that the confinement of binary salts yielded the highest water uptake (0.88 gw/gads at 25 °C and 90 % RH), which was four times higher than that of the parent SAPO-34. The shape of the obtained water vapor isotherms revealed that the salts introduced into the porous structure led to significant changes in the sorption mechanism, with SAPO-34 following a Langmuir behavior (type I isotherm) and the composites a type II isotherm with associated multilayer formation due to the presence of the salts. Kinetic studies also revealed that the materials follow a PSO model dominated by water-surface interactions. Embedding different salts into the same hosting pores to support atmospheric water harvesting was therefore found to enhance capacity and cyclability compared to single inorganic porous structures toward more efficient water sorption processes.

The effect of inorganic salt modification of sludge on the performance of sludge-coal water slurry

Coal water slurry (CWS) is a coal-based liquid fuel with the characteristics of high efficiency and low pollution. Municipal sludge, as a substantial solid waste, is of increasing attention due to the severe environmental pollution and difficult disposal. In this study, sludge is modified by inorganic salt solution and then used to prepare salt-modified sludge coal water slurry (SSCWS). The results showed that the sludge modified by KCl and AlCl3 can reduce the viscosity of CWS. While low concentration of CaCl2 tends to slightly increase the viscosity of CWS and higher concentration of CaCl2 can reduce the viscosity. It was found that among the three salts used in the experiment, the higher the cation valence state is, the easier and more the dispersant molecules are adsorbed on the surface of coal or sludge particles to improve the dispersion of coal and sludge particles, which was the main reason for improving the slurryability of SSCWS.

Cyclodextrin-Calcium Carbonate Micro- to Nano-Particles: Targeting Vaterite Form and Hydrophobic Drug Loading/Release

Tailor-made and designed micro- and nanocarriers can bring significant benefits over their traditional macroscopic counterparts in drug delivery applications. For the successful loading and subsequent release of bioactive compounds, carriers should present a high loading capacity, trigger release mechanisms, biodegradability and biocompatibility. Hydrophobic drug molecules can accumulate in fat tissues, resulting in drawbacks for the patient's recovery. To address these issues, we propose to combine the advantageous features of both host molecules (cyclodextrin) and calcium carbonate (CaCO3) particles in order to load hydrophobic chemicals. Herein, hybrid cyclodextrin-CaCO3 micro- to nano-particles have been fabricated by combining Na2CO3 solution and CaCl2 solution in the presence of an additive, namely poly (vinylsulfonic acid) (PVSA) or glycerol (gly). By investigating experimental parameters and keeping the Na2CO3 and CaCl2 concentrations constant (0.33 M), we have evidenced that the PVSA or gly concentration and mixing time have a direct impact on the final cyclodextrine-CaCO3 particle size. Indeed, by increasing the concentration of PVSA (5 mM to 30 mM) or gly (0.7 mM to 4 mM) or the reaction time (from 10 min to 4 h), particles with a size of 200 nm could be reached. Interestingly, the vaterite or calcite form could also be selected, according to the experimental conditions. We hypothesised that the incorporation of PVSA or gly into the precipitation reaction might reduce the nucleation rate by sequestering Ca2+. The obtained particles have been found to keep their crystal structure and surface charge after storage in aqueous media for at least 6 months. In the context of improving the therapeutic benefit of hydrophobic drugs, the developed particles were used to load the hydrophobic drug tocopherol acetate. The resulting particles are biocompatible and highly stable in a physiological environment (pH 7.4, 0.15 M NaCl). A selective release of the cargo is observed in acidic media (pH lower than 5).

Chloride desorption mechanisms of cement pastes containing fly ash

The chemical and physical bonds between cement hydrates and chlorides in concrete can immobilize ingressed chlorides and slow free chloride transport in the concrete pore solution. However, the disassociation of bound chlorides due to reduced pH is an unfavorable mechanism because it increases the concentration of free chlorides and the risk of corrosion in reinforced concrete structures. This study investigated the binding and desorption of chlorides in ordinary portland cement (OPC) and blended paste samples containing 15 % and 30 % fly ash. Paste samples were exposed to various concentrations of NaCl, CaCl2, and MgCl2 solutions to assess their chloride binding capacities. Subsequently, they were exposed to various volumes of 1 M nitric acid to study the influence of the pH of the exposure solution on chloride desorption. The results showed that incorporating 15 % and 30 % fly ash increased the chloride binding capacity of the paste samples by 1.76 and 2.16 times compared to OPC. The disassociation of bound chlorides was influenced by the fly ash replacement level, salt cation, and pH of the exposure solution. Increased fly ash replacement levels inhibited chloride desorption and led to the retention of more bound chlorides when the pH decreased.

Calcium Alginate Production through Forward Osmosis with Reverse Solute Diffusion and Mechanism Analysis

Calcium alginate (Ca-Alg) is a novel target product for recovering alginate from aerobic granular sludge. A novel Ca-Alg production method was proposed herein where Ca-Alg was formed in a sodium alginate (SA) feed solution (FS) and concentrated via forward osmosis (FO) with Ca2+ reverse osmosis using a draw solution of CaCl2. An abnormal reverse solute diffusion was observed, with the average reverse solute flux (RSF) decreasing with increasing CaCl2 concentrations, while the average RSF increased with increasing alginate concentrations. The RSF of Ca2+ in FS decreased continuously as the FO progressed, using 1.0 g/L SA as the FS, while it increased initially and later decreased using 2.0 and 3.0 g/L SA as the FS. These results were attributed to the Ca-Alg recovery production (CARP) formed on the FO membrane surface on the feed side, and the percentage of Ca2+ in CARP to total Ca2+ reverse osmosis reached 36.28%. Scanning electron microscopy and energy dispersive spectroscopy also verified CARP existence and its Ca2+ content. The thin film composite FO membrane with a supporting polysulfone electrospinning nanofiber membrane layer showed high water flux and RSF of Ca2+, which was proposed as a novel FO membrane for Ca-Alg production via the FO process with Ca2+ reverse diffusion. Four mechanisms including molecular sieve role, electrification of colloids, osmotic pressure of ions in CARP, and FO membrane structure were proposed to control the Ca-Alg production. Thus, the results provide further insights into Ca-Alg production via FO along with Ca2+ reverse osmosis.

First‐Principles Molecular Dynamics Study on Ionic Structure and Transport Properties of NaCl‐MgCl2‐CaCl2 Ternary Molten Salt System

AbstractThe carbochlorination in molten salt is an effective method for titanium extraction form low‐grade titanium slag with a high calcium and magnesium content. However, in industrial practice, the fluidity of molten salt will gradually decrease with the increase of CaCl2 content. It is important to elucidate the influencing mechanism of CaCl2 content on the microstructure and diffusion properties of molten salt for the rational selection of a molten salt system and clean utilization of titanium slag. In this study, the densities of molten salt systems with different CaCl2 contents are measured according to the Archimedes principle. Then, using the first‐principles molecular dynamics (FPMD) method, the ionic structure and transport properties of NaCl‐MgCl2‐CaCl2 ternary molten salt systems under different CaCl2 contents are qualitatively and quantitatively described by determining the partial radial distribution functions (PRDF), coordination number (CN), angular distribution functions (ADF), and diffusion coefficient (DC). The results show that with the addition of CaCl2, Ca2+ ion complexed with Cl− ion to form larger ionic clusters, which reduced the proportion of free Cl− ion and restricted the diffusion of Cl− ion.